I got a mew.
They were doing these mall tours, and aside from getting a mew (and a certificate to prove it was a real mew), there was a tournament with two rounds. If you won both rounds, you got two pogs with a boulder and a cascade badge on them, and entered for a chance to face off against a "gym leader".
I got both badges but didn't get to battle the gym leader, which was good because they were stupidly tough because they were using proper strategies while all the kids like me were just using mewtwo and seeing how far that for us.
I remember one of the gym leaders had a Starmie, with Double Team. Remember that Double Team is a move so good it's banned in most competitions.
The only person to beat the leader while I was watching was some guy in his twenties, and as a kid I remember thinking he was too old to be playing pokemon.
How time makes a fool of us all...